Exemplary embodiments relate to a package apparatus and, more particularly, to a package apparatus and a method of operating the same, wherein data stored in the content-addressable memory (CAM) cell of a nonvolatile memory chip is loaded after a power source has stabilized.
Recently, with an increasing demand for mobile products, such as camcorders, digital cameras, portable phones, and MPEG-1 Layer3 (MP3) players, attempts are being made to further improve the operating performance of the mobile products.
Internal options for a nonvolatile memory device applied to a specific mobile product are determined so that they comply with the operating characteristics of the mobile product, and so the nonvolatile memory device is operated in accordance with a corresponding application program.
With the development of new technologies, the number of application programs for a specific mobile product has increased. Accordingly, there is a growing need for techniques for reliably assigning various options to a corresponding nonvolatile memory device.
In the past, option information was stored in the fuse, etc. of a nonvolatile memory device. However, because of the large area occupied by a fuse, option information is now often stored in the CAM cell of a nonvolatile memory device. The amount and degree of integration of nonvolatile memory devices is increasing.
A nonvolatile memory device, in which the option information is stored in a CAM cell, when being powered up, needs to perform an operation of loading data stored in the CAM cell during a reset operation and then storing the loaded data in an internal register. The operation of loading the data of the CAM cell is performed after the voltage has stabilized to a certain voltage level.
A large amount of current is necessary for the operation of loading the data of the CAM cell. Accordingly, a nonvolatile memory device determines whether the voltage has stabilized and then performs the operation of loading the data of the CAM cell after the voltage has stabilized.
Some packages, each including a nonvolatile memory device, are configured to load data stored in a CAM cell in response to a command generated by an external controller. In this case, after voltage supplied to the external controller has stabilized, the external controller inputs a command to a corresponding nonvolatile memory chip so that it loads the data of the CAM cell.
Here, the voltage supplied to the nonvolatile memory chip is stabilized at a later point in time than the voltage supplied to the external controller. In this case, since the operation of loading the data of the CAM cell, which requires a large amount of current, is performed in a state in which the voltage supplied to the nonvolatile memory chip has not yet stabilized, a malfunction can occur in loading the data of the CAM cell.
FIG. 1 is a graph showing a comparison between the time taken for the voltage of an external controller to stabilize and the time taken for the voltage of a memory chip to stabilize.
This figure shows the difference between the time taken for the voltage supplied to a memory chip to stabilize and the time taken for the voltage supplied to an external controller to stabilize.
If a command to load data stored in a CAM cell is inputted after the voltage supplied to the external controller has stabilized and before the voltage supplied to the memory chip has stabilized, an error results in reading the data of the CAM cell because the voltage supplied to the memory chip has not yet stabilized.
If the data of the CAM cell is loaded after the voltage of the memory chip has stabilized, the data of the CAM cell can normally be read without error. However, the known external controllers are unable to determine whether the voltage of the memory chip has stabilized.